Hadrian: Add option to generate .hie files
The +hie_files flavour transformer can be enabled to produce hie files for stage1 libraries. The hie files are produced in the "extra-compilation-artifacts" folder and copied into the resulting bindist.
At the moment the hie files are not produced for the release flavour, they add about 170M to the final bindist.
Towards #16901
Edited by Matthew Pickering